The primary objective of this research is to develop and experimentally evaluate a comprehensive treatment program for socially withdrawn preschool children. Evidence was presented to indicate that social interaction with peers is essential to healthy development, that social withdrawal is relatively stable, and that young children who show a consistent pattern of social isolation are likely to be at risk for later social, psychological, and academic difficulties. A central issue is the identification of specific skills that contribute to social adjustment. Delineating them would provide more specificity for developing precise remediation procedures. A social learning analysis suggests that 4 skill areas may be critical predictors of social adjustment: a child's (a) social, (b) physical, and (c) language/communication skills, and (d) the parents' childrearing skills. The present study will empirically assess the contribution of these skills to social adjustment. A comprehensive index of sociability will be based on ratings by peers, teachers, and parents supplemented by direct observations of social interaction. A sample of 250 preschoolers aged 3-6 will be comprehensively assessed during each of two years. Multiple regression analysis will identify the relative contributions of skill levels to the index of sociability. Stability of the measures will be examined to assess the effects of developmental growth. Sociability scores less than 1 s.d. below the mean will identify the withdrawn sample. Cutoff scores demarcating deficits in significant skill areas will be those most accurately discriminating withdrawn from nonwithdrawn children. Skill training to improve deficits will be provided to a randomly selected experimental group while a matched control group remains untreated. Analyses will assess the effects of skill training on sociability scores. Followup assesments at the beginning and end of the last year will be conducted. Between assessments, skill training will be provided those children still withdrawn to replicate the effects of the previous year.